You are not the only one who has heard differences in power cords, or heard differences where there should be none. I too, have heard those differences. And I can tell you, the experience was really quite convincing. I could have sworn till I was blue in the face that the difference was real. But once the swap is done a few times, I became less confident. And under blind conditions, the difference went away.
I can also tell you that I sometimes can not hear differences where I know there should be one. For example, I have different DSP settings on my system, and there are measurable differences between the settings. I have two speakers and two subs, and I retuned my DSP asking the question: does it sound better if I give more bass to the speakers, or more bass to the subs? Both were equalized to the same target, and I sat down to listen. I honestly don't think I could pass a blind test - the difference, if there is one, is extremely subtle! Lesson: your hearing isn't as reliable as you think.
I also know what happens next. After your short and unreliable auditory memory failed you, you come on to forums to say you heard a difference in power cords. Depending on the forum, your view is either accepted or rejected. If the former happens, it is affirmation - you go away believing that audible differences exist. If the latter happens, your defensiveness kicks in. It becomes difficult to back down. I know, because I have been there. In fact, I think a lot of us have probably been there, but maybe some of us are unwilling to admit it. It's okay, we make mistakes, we say silly things on forums. Best to put ego away, be humble, and be honest with yourself. In the long run, it's better for you, and people respect you more when they see you are willing to admit mistakes and learn.